Supply method and supply system for polymer flocculant solution

Abstract

To provide a supply method for a polymer flocculant solution that can supply an appropriate polymer flocculant solution, following change of a condition of a flocculation tank.SOLUTION: A supply method for a polymer flocculant solution includes: a step A1 of measuring one or more conditions that are selected based on flow volumes of water to be treated flowing into a flocculation tank, an aspect of the water to be treated flowing into the flocculation tank and a flocculation situation of a flocculated flock in the flocculation tank; a step A2 of determining a dissolution concentration X1 of a polymer flocculant in a polymer flocculant solution to be supplied to the flocculation tank, at least on the basis of a measured result in the step A1; a step A3 of supplying a water-based solvent and the polymer flocculant into a dissolving / retaining tank, at a ratio at which the polymer flocculant solution with the dissolution concentration X1 can be obtained; a step A4 of dissolving the polymer flocculant in the dissolving / retaining tank while stirring the polymer flocculant in the water-based solvent, to prepare the polymer flocculant solution; and a step A5 of supplying the polymer flocculant solution prepared in the step A4 to the flocculation tank.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for supplying a polymer flocculant solution, and also to a system for supplying a polymer flocculant solution. [Background technology]

[0002] A known water purification process (water supply treatment) involves coagulation and sedimentation of raw water that has passed through a receiving well in a coagulation and sedimentation treatment facility that has a coagulation and mixing basin (hereinafter referred to as the "mixing basin"), a flocculation basin, and a settling basin, and then filtering the coagulation and sedimentation-treated water (hereinafter referred to as the "treated water") in a rapid sand filter filled with filtering material, after which a disinfectant is added to produce tap water. In the coagulation and sedimentation process and rapid sand filter in such water purification processes, a method is widely used in which a coagulant is added to form coagulated flocs, and the coagulated flocs are then removed by solid-liquid separation to obtain treated water.

[0003] Traditionally, inorganic flocculants such as aluminum sulfate and polyaluminum chloride (PAC) have been the mainstream flocculants, but inorganic flocculants have the disadvantage that it is difficult to form sufficiently large flocs, and the solid-liquid separation speed in the flocculation sedimentation and filtration process is slow. For this reason, the use of polymer flocculants has recently been considered to improve the settling properties of flocs. Since polymer flocculants are in powder form, they are generally used by dissolving them in water or other aqueous solvents. For this reason, a device for dissolving and storing the polymer flocculant is required.

[0004] Conventionally, in devices for dissolving and storing polymer flocculants, various ideas have been proposed for efficiently adjusting the polymer flocculant solution in which short fibers are dispersed, and for accurately adjusting the concentration of the polymer flocculant solution to a target concentration.

[0005] Patent Document 1 describes an apparatus for carrying out a method for preparing a polymer flocculant aqueous solution, the apparatus having a dissolving / dispersing tank in which a polymer flocculant is dissolved and short fibers are dispersed, and a stirring means for stirring the liquid in the dissolving / dispersing tank. The upper part of the dissolving / dispersing tank is provided with a solvent injection means for injecting an aqueous solvent into the dissolving / dispersing tank, an addition means capable of adding a polymer flocculant to the dissolving / dispersing tank, and an input means capable of inputting short fibers into the dissolving / dispersing tank.

[0006] In addition, it is described that a viscosity detection means is installed inside the dispersion tank of the adjustment device described in Patent Document 1, and the swelling state of the polymer flocculant is grasped. And, when it is determined that the viscosity of the liquid in the dispersion tank exceeds 10 mPa·s, it is described that short fibers are added, and when it is determined that the viscosity of the liquid is less than 10 mPa·s, it is described that the stirring of the dispersion tank is returned. This makes it possible to disperse short fibers in the swollen state of the polymer flocculant.

[0007] Patent Document 2 describes a polymer flocculant dissolving apparatus equipped with a concentration measuring device, which is characterized by having a polymer flocculant supply system that supplies powdered polymer flocculant and is equipped with a weighing means for the supplied polymer flocculant, a water supply system that supplies water and is equipped with a water amount adjustment means for adjusting the amount of water supplied, a dissolution tank that introduces the polymer flocculant supplied from the polymer flocculant supply system and the water supplied from the water supply system to prepare a polymer flocculant aqueous solution, a concentration measuring device that measures the concentration of the polymer flocculant aqueous solution in the dissolution tank, and a control means that sends a signal to the polymer flocculant supply system or / and the water supply system indicating the amount of polymer flocculant to be added and / or the amount of water to be added so that the measured concentration becomes a target value based on the concentration measured by the concentration measuring device. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2016-097345 A [Patent Document 2] JP 2002-136805 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, the conditions of the coagulation tank, such as the flow rate of the water to be treated flowing into the coagulation tank, such as a mixing basin or a rapid filtration basin, where coagulated flocs are formed by adding a polymer coagulant solution, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulated flocs in the coagulation tank, are not constant but fluctuate. Therefore, the appropriate concentration and flow rate of the polymer coagulant solution to be supplied to the coagulation tank also fluctuate. However, in the past, there was no consideration of adjusting the concentration and flow rate of the polymer coagulant solution according to the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulated flocs in the coagulation tank, and there was room for improvement in the method of supplying the polymer coagulant solution to the coagulation tank.

[0010] The present invention has been created in consideration of the above circumstances, and in one embodiment, it is an object of the present invention to provide a method for supplying a polymer flocculant solution that makes it possible to supply an appropriate polymer flocculant solution in accordance with changes in the conditions of the flocculation tank. In another embodiment, it is an object of the present invention to provide a system for supplying a polymer flocculant solution that is suitable for carrying out such a supply method. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above problems, and have found that it is possible to supply an appropriate polymer flocculant solution to the coagulation tank by measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank, and by preparing a polymer flocculant solution of an appropriate concentration or changing the concentration of an existing polymer flocculant solution based at least on the measurement results. The present invention has been completed based on this finding, and is exemplified below.

[0012] [Aspect 1] A step A1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; A step A2 of determining a dissolved concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based at least on the measurement result in the step A1; A step A3 of supplying an aqueous solvent and a polymer flocculant to a dissolution storage tank in a ratio such that a polymer flocculant solution having a dissolution concentration of X1 is obtained; A step A4 of dissolving the polymer flocculant in the dissolution storage tank in the aqueous solvent while stirring to prepare a polymer flocculant solution; A step A5 of supplying the polymer flocculant solution prepared in the step A4 to a flocculation tank; Including, A method for supplying a polymer flocculant solution. [Aspect 2] The method for supplying a polymer flocculant solution according to embodiment 1, comprising carrying out step A4 under conditions of a stirrer rotation speed and a stirring time determined based on the dissolved concentration X1. [Aspect 3] A step B1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; A step B2 of determining a dissolved concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based at least on the measurement result in the step B1; A step B3 of determining the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank; A step B4 of comparing X1 and X2; When X1>X2, a step B5 of determining the amount of polymer flocculant required to obtain a polymer flocculant solution having a dissolution concentration of X1 based on the dissolution concentration X1, the dissolution concentration X2, and the amount of the polymer flocculant solution already in the dissolution storage tank; Step B6 of supplying the amount of polymer flocculant determined in step B5 to the dissolution storage tank; A process B7 of dissolving the polymer flocculant supplied to the dissolution storage tank in the existing polymer flocculant solution while stirring to prepare a polymer flocculant solution with a changed concentration; Step B8 of supplying the polymer flocculant solution with a changed concentration prepared in Project B7 to the flocculation tank including A method for supplying a polymer flocculant solution [Aspect 4] Step C1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank, the properties of the water to be treated flowing into the flocculation tank, and the flocculation state of the flocculated flocs in the flocculation tank Step C2 of determining the dissolved concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based at least on the measurement results in Step C1 Step C3 of determining the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank Step C4 of comparing X1 and X2 When X1 < X2, based on the dissolved concentration X1, the dissolved concentration X2, and the amount of the existing polymer flocculant solution in the dissolution storage tank, Step C5 of determining the amount of the aqueous solvent required to obtain the polymer flocculant solution with the dissolved concentration X1 Step C6 of supplying the amount of the aqueous solvent determined in Step C5 to the dissolution storage tank Step C7 of stirring the aqueous solvent supplied to the dissolution storage tank together with the existing polymer flocculant solution to prepare a polymer flocculant solution with a changed concentration Step C8 of supplying the polymer flocculant solution with a changed concentration prepared in Step C7 to the flocculation tank including A method for supplying a polymer flocculant solution [Aspect 5] Step D1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank, the properties of the water to be treated flowing into the flocculation tank, and the flocculation state of the flocculated flocs in the flocculation tank Step D2 of determining the dissolved concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based at least on the measurement results in Step D1 Step D3 of determining the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank Step D4 of comparing X1 and X2 When X1 < X2, while supplying an aqueous solvent to an injection line at a flow rate ratio at which a polymer flocculant solution having a dissolution concentration of X1 is obtained, simultaneously supplying an existing polymer flocculant solution from a dissolution storage tank to the injection line, and mixing the two by a mixing device in the injection line to prepare a polymer flocculant solution changed to a dissolution concentration of X1, step D5; Step D6 of supplying the polymer flocculant solution with the changed concentration to a flocculation tank via an injection line; including A method for supplying a polymer flocculant solution. [Aspect 6] A measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank, the properties of the water to be treated flowing into the flocculation tank, and the flocculation state of the flocculated flocs in the flocculation tank; A dissolution storage tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supply device for supplying a polymer flocculant to the dissolution storage tank; A solvent supply line for supplying an aqueous solvent to the dissolution storage tank; A stirrer installed in the dissolution storage tank; An injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; A control device having a calculation unit and a control unit; equipped with The calculation unit can determine the dissolution concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measuring device, The control unit can control the amount of the aqueous solvent supplied from the solvent supply line to the dissolution storage tank and the amount of the polymer flocculant supplied from the polymer flocculant supply device to the dissolution storage tank so that a polymer flocculant solution having a dissolution concentration of X1 is obtained. A supply system for a polymer flocculant solution. [Aspect 7] The calculation unit of the control device can determine the conditions of the rotation speed and stirring time of the stirrer based on the dissolution concentration X1, and the control unit of the control device can operate the stirrer under the said conditions. The supply system of the polymer flocculant solution according to Aspect 6. [Aspect 8] a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; a dissolving and storing tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supplying device for supplying the polymer flocculant to the dissolution storage tank; a solvent supply line for supplying the aqueous solvent to the dissolution reservoir; A stirrer installed in the dissolution storage tank; an injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; A concentration meter capable of measuring the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank; A control device having a calculation unit and a control unit; Equipped with However, if the control device has a memory unit capable of storing information on the dissolved concentration of the polymer flocculant targeted when preparing the existing polymer flocculant solution in the dissolution storage tank, and the dissolved concentration can be regarded as the dissolved concentration X2, the concentration meter may not be required. The calculation unit determines the dissolution concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement results by the measurement device, compares the dissolution concentration X1 with the dissolution concentration X2, and when X1>X2, determines the amount of polymer flocculant required to obtain a polymer flocculant solution with a dissolution concentration X1 based on the dissolution concentration X1, the dissolution concentration X2, and the amount of polymer flocculant solution already in the dissolution storage tank. The control unit can control the amount of polymer flocculant supplied from the polymer flocculant supply device to the dissolution storage tank according to the determination of the calculation unit. Polymer flocculant solution supply system. [Aspect 9] a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; A dissolution and storage tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution, A polymer flocculant supply device for supplying a polymer flocculant to the dissolution and storage tank, A solvent supply line for supplying an aqueous solvent to the dissolution and storage tank, A stirrer installed in the dissolution and storage tank, An injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution and storage tank into the coagulation tank, A concentration meter capable of measuring the dissolution concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution and storage tank, A control device having a calculation unit and a control unit, Comprising However, when the control device has a storage unit capable of storing information on the dissolution concentration of the target polymer flocculant when preparing the existing polymer flocculant solution in the dissolution and storage tank, and it is possible to regard the dissolution concentration as the dissolution concentration X2, the concentration meter may not be necessary. The calculation unit determines the dissolution concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the coagulation tank based on the measurement result of the measuring device, compares the dissolution concentration X1 with the dissolution concentration X2, and when X1 < X2, based on the dissolution concentration X1, the dissolution concentration X2, and the amount of the existing polymer flocculant solution in the dissolution and storage tank, it is possible to determine the amount of the aqueous solvent required to obtain the polymer flocculant solution with the dissolution concentration X1. The control unit can control the amount of the aqueous solvent supplied from the solvent supply line to the dissolution and storage tank according to the determination of the calculation unit. A supply system for a polymer flocculant solution. [Aspect 10] A measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank, A dissolution and storage tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution, A polymer flocculant supply device for supplying a polymer flocculant to the dissolution and storage tank, A first solvent supply line for supplying an aqueous solvent to the dissolution and storage tank, A stirrer installed in the dissolution storage tank, An injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank, A second solvent supply line for supplying an aqueous solvent to the injection line, A mixing device for mixing the polymer flocculant solution flowing through the injection line and the aqueous solvent flowing through the second solvent supply line, A concentration meter capable of measuring the dissolution concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank, A control device having a calculation unit and a control unit, Comprising, However, when the control device has a storage unit capable of storing information on the dissolution concentration of the target polymer flocculant when preparing the existing polymer flocculant solution in the dissolution storage tank, and it is possible to regard the dissolution concentration as the dissolution concentration X2, the concentration meter may not be provided. The calculation unit determines the dissolution concentration X1 of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measuring device, compares the dissolution concentration X1 with the dissolution concentration X2, and when X1 < X2, determines the ratio of the existing polymer flocculant solution and the aqueous solvent such that a polymer flocculant solution with a dissolution concentration of X1 can be obtained. The control unit can control the flow rate of the aqueous solvent supplied to the injection line via the second solvent supply line and the flow rate of the existing polymer flocculant solution supplied from the dissolution storage tank to the injection line so as to be the ratio according to the determination of the calculation unit. A polymer flocculant solution supply system.

Advantages of the Invention

[0013] According to the method and system for supplying a polymer flocculant solution according to one embodiment of the present invention, it is possible to supply an appropriate polymer flocculant solution in response to changes in the conditions of the coagulation tank. As a result, even if the conditions of the coagulation tank, such as the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the flocs in the coagulation tank, change, it becomes possible to stably form flocs in the coagulation tank. The method and system for supplying a polymer flocculant solution are widely applicable to coagulation and sedimentation processes in water supply and sewage treatment and various types of wastewater treatment. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a configuration of a polymer flocculant solution supply system according to an embodiment of the present invention. [Diagram 2] 1 is a flowchart of a method for supplying a polymer flocculant solution according to one embodiment of the present invention, in the case where a new polymer flocculant solution is prepared and supplied. [Diagram 3] 1 is a flowchart of a method for supplying a polymer flocculant solution according to one embodiment of the present invention, in the case where a polymer flocculant solution having a changed concentration is prepared and supplied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <1. Polymer flocculant solution supply system> FIG. 1 shows a schematic diagram of a supply system 100 for a polymeric flocculant solution 114 according to one embodiment of the present invention. The polymer flocculant solution 114 supply system 100 includes: a measuring device 192 for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulated flocs in the coagulation tank 191; A dissolving storage tank 110 capable of dissolving a polymer flocculant 125 in an aqueous solvent and storing a polymer flocculant solution 114; A polymer flocculant supplying device 120 for supplying a polymer flocculant 125 to the dissolution storage tank 110; a first solvent supply line 130 for supplying an aqueous solvent to the dissolution reservoir 110; A stirrer 140 installed in the dissolution storage tank 110; An injection line 181 for injecting the polymer flocculant solution 114 discharged from the outlet 112 of the dissolution storage tank 110 into the flocculation tank 191; A concentration meter 150 capable of measuring the dissolved concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114 in the dissolution storage tank 110; A transparency meter 160 for measuring the transparency of the polymer flocculant solution 114 in the dissolution storage tank 110; A control device 200 having a calculation unit 210 and a control unit 220; Equipped with. However, if the control device 200 has a memory unit 230 capable of storing the intended dissolution concentration of the polymer flocculant 125 when preparing the existing polymer flocculant solution 114 in the dissolution storage tank 110, and the dissolution concentration can be regarded as the dissolution concentration X2, then the concentration meter 150 is not necessary.

[0016] The coagulation tank 191 into which the polymer coagulant solution 114 is injected is not particularly limited as long as it is a water tank in which the formation of coagulated flocs is required. Examples include a coagulation sedimentation treatment facility and a rapid sand filter in a water purification facility. The water to be treated flowing into the coagulation tank 191 may be treated process water that has undergone various treatment steps before the injection point of the polymer coagulant solution 114, or may be untreated process water that has not undergone any treatment steps. For example, when the water is injected into a coagulation sedimentation treatment facility located in the middle of the raw water line in the water purification process, the coagulation tank 191 can be a mixing tank. As the raw water, river water, lake water, reservoir water, subsurface water, groundwater, etc. can be used. As the water to be treated, in addition to raw water to be treated in a water purification facility, wastewater to be treated in a wastewater treatment facility or the like can also be used, and there is no restriction on the water to be treated and the facility to treat it. From the viewpoint of promoting floc formation, it is preferable that the injection point 185A of the polymer coagulant solution 114 is provided downstream of the injection point 185B of the inorganic coagulant. Further, the polymer flocculant 125 may be used not only in coagulation and sedimentation, but also as a filter aid before the filtration basin, and may be used in a plurality of processes such as coagulation and sedimentation and filtration.

[0017] In one embodiment, the supply system 100 of the polymer flocculant solution 114 includes various flow path switching valves 131a, 131b, 131c, 131d, and 131e. As the flow path switching valves, electrically driven valves such as motorized valves and solenoid valves capable of realizing the necessary flow path switching function can be used. For example, electrically driven three-way valves and four-way valves can be used. In one embodiment, the supply system 100 of the polymer flocculant solution 114 can include a pump 182 in the middle of the injection line 181.

[0018] The conditions of the coagulation tank 191, such as the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulated flocs in the coagulation tank 191, are not constant but fluctuate. Therefore, measuring one or more, preferably two or more, more preferably three selected from these conditions and reflecting the measurement results in the preparation conditions and / or supply conditions of the polymer coagulant solution 114 is useful in supplying an appropriate polymer coagulant solution 114 to the coagulation tank 191 and forming stable coagulated flocs.

[0019] The measuring devices 192 (192A, 192B, 192C) are capable of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulated flocs in the coagulation tank 191. Depending on the condition to be measured, the measuring devices 192 include measuring device 192A installed in an upstream piping through which the water to be treated flowing into the coagulation tank 191 flows, measuring device 192B installed in a downstream piping through which the water to be treated flowing out of the coagulation tank 191 flows, and measuring device 192C installed in the coagulation tank 191.

[0020] Examples of the measuring device 192 for measuring the flow rate of the water to be treated flowing into the coagulation tank 191 include a flow meter installed in an upstream pipe through which the water to be treated flowing into the coagulation tank 191 flows, and a water level measuring device such as a level meter and a level switch installed in the coagulation tank 191. Examples of the measuring device 192 for measuring the properties of the water to be treated flowing into the coagulation tank 191 include a turbidity meter, a total organic carbon (TOC) meter, a color meter, a pH meter, and a residual chlorine concentration meter installed in an upstream pipe through which the water to be treated flowing into the coagulation tank 191 flows. Examples of the measuring device 192 for measuring the coagulation state of the coagulation flocs in the coagulation tank 191 include a turbidity meter for measuring the turbidity of the supernatant water, a total organic carbon (TOC) meter, a color meter, a pH meter, and a residual chlorine concentration meter installed in a downstream pipe through which the water to be treated flowing out of the coagulation tank 191 flows. When good flocculation has been formed, the turbidity of the supernatant water is less than 0.5 degrees (formazin) when measured in accordance with JIS K0101:2017 "Testing method for industrial water."

[0021] The coagulation tank 191 may be composed of a single tank or multiple tanks. For example, as shown in the figure, in one embodiment, the coagulation tank 191 may have, from the upstream side to the downstream side, a rapid stirring tank 191B, a slow stirring tank 191A, and a settling tank 191C in this order.

[0022] The measurement results by the measuring device 192 can be used when there is no polymer flocculant solution 114 remaining in the dissolution storage tank 110 and a new polymer flocculant solution is to be prepared. The measurement results by the measuring device 192 can also be used when the polymer flocculant solution 114 remaining in the dissolution storage tank 110 is used to prepare a polymer flocculant solution 114 with a changed concentration. The latter is particularly advantageous in that when the conditions in the flocculation tank 191 change suddenly, an appropriate polymer flocculant solution 114 can be quickly supplied to the flocculation tank 191 without wasting the existing polymer flocculant solution 114.

[0023] The polymer flocculant supplying device 120 may be a known fixed quantity feeder for powdered or granular materials, and is not particularly limited. Referring to the partially enlarged view of FIG. 1, in one embodiment, the polymer flocculant supplying device 120 includes a polymer flocculant storage tank 122, a weighing means 124, a supply port 126, and a vibration damper 128. A hopper or the like can be used as the polymer flocculant storage tank 122, and the polymer flocculant 125 can be stored therein. The polymer flocculant 125 is generally in a powder form. The weighing means 124 is provided below the polymer flocculant storage tank 122. The polymer flocculant 125 drawn out from the polymer flocculant storage tank 122 is weighed by the weighing means 124, and then a predetermined amount of the polymer flocculant 125 is supplied from the supply port 126 to the dissolution storage tank 110. For example, as shown in the figure, the polymer flocculant 125 can be dropped by gravity from the supply port 126 and supplied to the dissolution storage tank 110. Alternatively, the polymer flocculant 125 may be supplied to the dissolution storage tank 110 by air pressure from the supply port 126. When the polymer flocculant 125 is supplied to the dissolution storage tank 110, if the supply speed is too high, undissolved portions are likely to be generated. For this reason, it is preferable to control the supply speed of the polymer flocculant 125 to the dissolution storage tank 110. The supply speed can be controlled, for example, by using the flow control function of a quantitative feeder. In addition, a vibration damper 128 can be installed in the polymer flocculant storage tank 122. This makes it easier for the polymer flocculant 125 to flow by the vibration of the vibration damper 128, and allows the quantitative measurement by the weighing means 124 to be performed smoothly. In one embodiment, the polymer flocculant supply device 120 can be controlled by the control device 200.

[0024] The dissolution reservoir 110 can be supplied with a fixed amount of the aqueous solvent from the first solvent supply line 130. Examples of means for enabling the fixed supply of the aqueous solvent include a flow control valve (not shown) installed in the first solvent supply line 130, and a water level measuring device (not shown) such as a level gauge or a level switch attached to the dissolution reservoir 110. Other means may be used. As the aqueous solvent, pure water, tap water, industrial water, well water, filtered water of purified treated water, etc. can be used, but pure water is preferred. In one embodiment, the supply of the aqueous solvent from the first solvent supply line 130 can be controlled by the control device 200.

[0025] In the illustrated embodiment, the dissolution storage tank 110 is configured as a single tank, but the function of the dissolution storage tank 110 may be realized by a single tank or by multiple tanks. For example, it may be divided into a dissolution tank for dissolving the polymer flocculant and a storage tank for the obtained polymer flocculant solution. There is no particular restriction on the capacity of the dissolution storage tank 110, but in one embodiment, an appropriate size can be achieved by setting the storage tank volume to a level that is consumed in 3 hours to 7 days, preferably 6 hours to 2 days.

[0026] The control device 200 is communicatively connected to devices to be monitored or operated wirelessly or by wire. In Fig. 1, the state in which the control device 200 is communicatively connected to the agitator 140, the concentration meter 150, the transparency meter 160, and the measurement device 192 is illustrated by dotted lines. In one embodiment, the control device 200 has a calculation unit 210, a control unit 220, a storage unit 230, an input unit 240, and an output unit 250.

[0027] The calculation unit 210 refers to a device and a circuit that executes a predetermined calculation according to a program based on input commands, instructions, and data, and data stored in the memory unit 230. The control unit 220 refers to a device and a circuit that issues a command to a control target according to a program based on input commands, instructions, and data, and data stored in the memory unit 230. For example, the control unit 220 can control the polymer flocculant supply device 120, the supply of the aqueous solvent from the first solvent supply line 130, the supply of the aqueous solvent from the second solvent supply line 132, various flow path switching valves 131a, 131b, 131c, 131d, and 131e, the agitator 140, the concentration meter 150, the transparency meter 160, the pump 182, and the measuring device 192. The various functions of the control unit 220 and the calculation unit 210 can be realized by a control / calculation device such as a central processing unit (CPU).

[0028] The memory unit 230 can be composed of devices and circuits that store various data, an operating system (OS), and programs for executing various arithmetic processing, and can use well-known memory devices, such as a primary memory device that mainly uses semiconductor memory, and a secondary memory device (auxiliary memory device) that mainly uses a hard disk drive or semiconductor disk.

[0029] The input unit 240 is an interface for providing data or commands to the calculation unit 210 and / or the control unit 220, and can be composed of a switch, a keyboard, a numeric keypad, a pointing device such as a mouse, a touch panel, a reader (OCR), an input screen, a voice input interface such as a microphone, etc.

[0030] The output unit 250 can be configured, for example, with a liquid crystal display, an organic electroluminescence display, or a printer.

[0031] In one embodiment, when an operator issues a command via the input unit 240, the control device 200 operates the measuring device 192 to measure a predetermined condition in the coagulation tank 191. The measurement result by the measuring device 192 may be output to the output unit 250. The command may be to immediately measure the condition, or to measure the condition at a predetermined date and time.

[0032] In one embodiment, the calculation unit 210 of the control device 200 can determine the dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result by the measurement device 192. In addition, the calculation unit 210 may determine the injection flow rate F1 of the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result by the measurement device 192, as necessary.

[0033] For example, if a database such as a spreadsheet in which the dissolved concentration X1 corresponding to the measurement results of the one or more conditions is stored in association with each other, a machine learning model for calculating the optimal dissolved concentration X1 corresponding to the measurement results of the one or more conditions, or an algorithm such as a formula capable of calculating the dissolved concentration X1 corresponding to the one or more conditions is stored in advance in the storage unit 230, the calculation unit 210 can determine the dissolved concentration X1 based on at least the measurement results of the one or more conditions. It is preferable to construct an algorithm that determines the dissolved concentration X1 taking into account other information in addition to the measurement results of the one or more conditions, such as one or both of the capacity of the dissolved storage tank 110 and the liquid delivery capacity of the pump 182.

[0034] The dissolution concentration X1 can be determined, for example, by collecting and analyzing data on how indicators showing the flocculation state of the flocs in the flocculation tank (e.g., floc diameter (size), floc compactness, floc density), floc settling velocity, supernatant water turbidity, and filtrate turbidity change while changing the one or more conditions and the dissolution concentration X1, and constructing an algorithm that links the one or more conditions with the dissolution concentration X1 that can obtain a desired flocculation state of the flocs. The state of the flocs may be analyzed by visual inspection or by image analysis of a photograph obtained by photographing the flocs. In this case, it is preferable to collect and analyze data by changing the dissolution concentration X1 as well as the injection flow rate F1. This makes it possible to determine the desired injection flow rate F1 as well as the desired dissolution concentration X1. In other words, it is possible to construct an algorithm that links the one or more conditions with the dissolution concentration X1 and the injection flow rate F1 that can obtain a desired flocculation state of the flocs. Furthermore, the dissolution concentration X1 and the injection flow rate F1 may be determined so as to minimize costs within a range in which a desired aggregation state of the aggregated flocs is obtained. Examples of costs to be considered include one or more selected from the cost of chemicals, the cost of aqueous solvents, and the cost of electricity. Of these, it is preferable to consider at least the cost of chemicals, which accounts for a large proportion of the total cost.

[0035] By collecting and analyzing data when changing the injection flow rate F1 in addition to the dissolved concentration X1, it is also possible to analyze the relationship between the injection rate of the polymer coagulant (=injection mass [mg] of polymer coagulant in the polymer coagulant solution per unit time / volume [L] of treated water flowing into the coagulation tank per unit time) and an index showing the coagulation status of the coagulation flocs.

[0036] The injection rate of the polymer flocculant may also be directly determined based on the measurement results of one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulated flocs in the coagulation tank 191. However, it is preferable to first determine the injection rate of the inorganic flocculant (= the injection mass [mg] of the inorganic flocculant in the inorganic flocculant solution per unit time / the volume [L] of the water to be treated flowing into the coagulation tank per unit time) based on the measurement results of the one or more conditions, and then determine the injection rate of the polymer flocculant according to the determined injection rate of the inorganic flocculant. This is because it is easier to obtain a good coagulation effect by determining the injection rate of the polymer flocculant in conjunction with the injection rate of the inorganic flocculant. The relationship between the injection rate of the inorganic flocculant and the injection rate of the polymer flocculant may be determined in advance by acquiring statistical data that indicates the quality of floc formation and precipitation. The injection rate of the polymer flocculant depends on the type of polymer flocculant used, but can be, for example, 0.005 to 2 times the injection rate of the inorganic flocculant.

[0037] The appropriate injection rate of the inorganic flocculant can be determined in advance based on the measurement results of the one or more conditions and the results of the jar test of the inorganic flocculant. For example, if a database such as a spreadsheet in which the injection rate of the inorganic flocculant corresponding to the measurement results of the one or more conditions is associated and stored, a machine learning model that calculates the optimal injection rate of the inorganic flocculant corresponding to the measurement results of the one or more conditions, or an algorithm such as a calculation formula that can calculate the injection rate of the inorganic flocculant according to the one or more conditions is stored in advance in the memory unit 230, the calculation unit 210 can determine the injection rate of the inorganic flocculant based at least on the measurement results of the one or more conditions.

[0038] When the flocs are in a desirable flocculation state, the floc diameter is, for example, 2 mm to 3 mm, but a larger diameter, for example, about 3 mm to 20 mm, may be preferable. The floc diameter (when the flocs are not perfectly round, it refers to the equivalent circular diameter) is often confirmed visually, but to improve accuracy and reproducibility, a ruler may be placed on the floc or an image measurement such as a photograph may be performed. When the flocs are in a desirable flocculation state, the floc settling velocity measured in accordance with the flocculation treatment test (jar test) described in Reference 5.1 of the "Guidelines for Design of Water Facilities 2012" (Japan Water Works Association) is, for example, 50 mm / min or more. However, since the floc settling velocity varies depending on the flocs being poorly packed and expanded, being light, containing air, etc., it may be determined by the facility manager's experience. When the flocs are in a desirable flocculation state, the supernatant water turbidity measured in accordance with JIS K0101:2017 "Testing Methods for Industrial Water" is less than 0.5 degrees (formazin). When the flocculation state of the flocs is desirable, the turbidity of the filtered water measured in accordance with the flocculation treatment test (jar test) described in Reference 5.1 of the "Guidelines for Design of Water Facilities 2012" (Japan Water Works Association) is less than 0.1 degrees.

[0039] It is preferable to construct the above algorithm so that one or more of the state of the flocs, the floc settling velocity, the supernatant turbidity, and the filtrate turbidity indicate a desired flocculation state of the flocs, it is more preferable to construct the above algorithm so that two or more of them indicate a desired flocculation state of the flocs, and it is even more preferable to construct the above algorithm so that all of them indicate a desired flocculation state of the flocs.

[0040] The injection flow rate F1 is preferably determined in consideration of the capacity of the dissolution storage tank 110. If the injection flow rate F1 is determined without considering the capacity of the dissolution storage tank 110, it is expected that the polymer flocculant solution 114 prepared in the dissolution storage tank 110 will run out in a short time. For this reason, it is desirable to determine the injection flow rate F1 on the condition that continuous injection is possible for at least one day, preferably at least seven days, when the dissolution storage tank 110 is filled with the polymer flocculant solution 114. Specifically, the capacity V (L) of the dissolution storage tank 110 and the injection flow rate F1 (L / min) preferably satisfy V≧24×60×F1, and more preferably satisfy V≧168×60×F1. However, when the injection flow rate F1 is reduced in consideration of the capacity of the dissolution storage tank 110, it is preferable to maintain the injection rate of the polymer flocculant by increasing the dissolution concentration X1.

[0041] In addition, since the pump 182 has a range (discharge rate range) within which the pump 182 can deliver liquid per unit time, the injection flow rate F1 is determined within the discharge rate range of the pump 182. For example, if the dissolution concentration X1 and the injection flow rate F1 are determined without taking into account the discharge rate of the pump 182, the injection flow rate F1 may be set to a value equal to or greater than the maximum discharge rate of the pump 182 (F max ), the injection rate of the polymer flocculant can be maintained by increasing the dissolution concentration X1, while keeping it within the range of the discharge rate of the pump 182. Conversely, when the injection flow rate F1 exceeds the minimum value (F min ), the injection rate of the polymer flocculant can be maintained by lowering the dissolution concentration X1, while keeping it within the range of the discharge rate of the pump 182.

[0042] General trends regarding one or more of the above conditions measured by the measuring device 192 and the dissolved concentration X1 and the injection flow rate F1 determined based at least on the measurement results of the conditions are shown below. The higher the flow rate of the water to be treated flowing into the coagulation tank, the higher the desired dissolved concentration X1 and the higher the desired injection flow rate F1. Conversely, the lower the flow rate of the water to be treated flowing into the coagulation tank, the lower the desired dissolved concentration X1 and the lower the desired injection flow rate F1. As a result of measurement by the measuring device 192, the worse the properties of the water to be treated flowing into the coagulation tank (e.g., the higher the turbidity), the higher the desired dissolved concentration X1 and the larger the desired injection flow rate F1. Conversely, as a result of measurement by the measuring device 192, the better the properties of the water to be treated flowing into the coagulation tank (e.g., the lower the turbidity), the lower the desired dissolved concentration X1 and the smaller the desired injection flow rate F1. The worse the floc coagulation state, the higher the desired dissolved concentration X1 and the larger the desired injection flow rate F1. Conversely, the better the floc coagulation state, the lower the desired dissolved concentration X1 and the smaller the desired injection flow rate F1. However, as described above, it is preferable to determine the dissolution concentration X1 and the injection flow rate F1 so as to obtain a desired flocculation state of the flocs, taking into consideration the capacity of the dissolution reservoir 110 and the range of the discharge rate of the pump 182.

[0043] (A. Preparation and supply of new polymer flocculant solution) When the target dissolution concentration X1 is determined, the control unit 220 can control the amount of the aqueous solvent supplied from the first solvent supply line 130 to the dissolution storage tank 110 and the amount of the polymer flocculant 125 supplied from the polymer flocculant supply device 120 to the dissolution storage tank 110, taking into consideration the injection flow rate F1 as necessary, so as to obtain the polymer flocculant solution 114 having the dissolution concentration X1. More specifically, the first flow path switching valve 131a, the flow control valve for the aqueous solvent (not shown), the polymer flocculant supply device 120, and the like can be operated to supply the aqueous solvent from the first solvent supply line 130 to the dissolution storage tank 110 and the polymer flocculant 125 from the polymer flocculant supply device 120 to the dissolution storage tank 110 at a ratio at which the polymer flocculant solution 114 having the dissolution concentration X1 is obtained. In one embodiment, the control device 200 can automatically execute the control of the equipment required for the preparation of the new polymer flocculant solution 114 when the target dissolution concentration X1 is determined.

[0044] The polymer flocculant may be selected from appropriate polymer flocculants depending on the application, but for example, when used in coagulation and precipitation treatment in water purification treatment, a polymer flocculant for water supply is used. The type of polymer flocculant for water supply is not particularly limited. For example, one or more selected from the group consisting of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, ammonium polyacrylate, polymethacrylic acid, sodium polymethacrylate, potassium polymethacrylate, and ammonium polymethacrylate can be used, with sodium polyacrylate being particularly preferred. The water treatment agent described in JP 2018-153729 A can also be suitably used. The polyacrylamide polymer flocculant is a copolymer of polyacrylamide and poly(meth)acrylate, and a commercially available product as an anionic polymer flocculant can be used.

[0045] When a predetermined amount of polymer flocculant 125 and aqueous solvent are introduced into the dissolution storage tank 110 at a blending ratio that results in a predetermined target concentration (for example, 0.01 to 0.2 mass %, depending on the turbidity of the water to be subjected to the coagulation and precipitation treatment), the polymer flocculant 125 dissolves in the aqueous solvent, and a polymer flocculant solution 114 is prepared. The timing at which the polymer flocculant 125 and the aqueous solvent are introduced into the dissolution storage tank 110 may be simultaneous, or either may be introduced first. However, in order to quickly dissolve the polymer flocculant 125 in the solvent, it is preferable to dissolve the polymer flocculant 125 by adding a weighed amount of the polymer flocculant 125 into the dissolution storage tank 110 while stirring the aqueous solvent in the dissolution storage tank 110 with the stirrer 140. In addition, stirring may be started before all the aqueous solvent is introduced into the dissolution storage tank 110, or after all the aqueous solvent is introduced. The stirring time may be appropriately set to a time sufficient for dissolving the polymer flocculant 125, and is not particularly limited, but may be, for example, about 1 to 2 hours. The rotation speed of the stirrer 140 is also not particularly limited, but may be, for example, 100 to 250 rpm.

[0046] In one embodiment, the control device 200 can determine the stirring conditions such as the rotation speed and stirring time of the stirrer 140 based on the dissolution concentration X1, and can operate the stirrer 140 under the conditions. For example, if a database such as a spreadsheet in which the stirring conditions such as the rotation speed and stirring time of the stirrer 140 corresponding to the dissolution concentration X1 are stored in association with each other, a machine learning model that calculates the optimum stirring conditions such as the rotation speed and stirring time of the stirrer 140 corresponding to the dissolution concentration X1, or an algorithm such as a calculation formula that can calculate the stirring conditions such as the rotation speed and stirring time of the stirrer 140 according to the dissolution concentration X1 is stored in advance in the storage unit 230, the calculation unit 210 can determine the stirring conditions such as the rotation speed and stirring time of the stirrer 140 based on the dissolution concentration X1. For example, when the dissolution concentration X1 is 1000 mg / L, it can be 150 rpm x 2 hr, and when the dissolution concentration X1 is 50 mg / L, it can be 150 rpm x 0.5 hr. The polymer flocculant solution can be efficiently prepared by lengthening the stirring time as the dissolution concentration X1 increases and shortening it as the dissolution concentration X1 decreases. Similarly to the stirring time, the rotation speed of the agitator 140 can be efficiently prepared by increasing the rotation speed as the dissolution concentration X1 increases and decreasing it as the dissolution concentration X1 decreases.

[0047] In one embodiment, the mixing conditions such as the rotation speed and mixing time of the mixer 140 may be set by an operator via the input unit 240. Also, mixing may be performed while monitoring the transparency of the dissolution reservoir tank 110 with the transparency meter 160, and the mixing may be terminated when the transparency satisfies a predetermined condition. The mixer 140 can operate under the set mixing conditions based on a command from the control unit 220.

[0048] The control device 200 is capable of operating the pump 182 and the flow path switching valves 131b, 131c, and 131e so that the polymer flocculant solution 114 in the dissolution storage tank 110 is injected from the outlet 112 of the dissolution storage tank 110 through the injection line 181 to the injection point 185A of the polymer flocculant solution 114.

[0049] It is preferable to use a metering pump capable of supplying a fixed amount as the pump 182. Although one pump may be used, a pump capable of supplying a relatively large flow rate and a pump capable of supplying a relatively small flow rate may be provided in parallel. For example, the large flow rate pump can be used to send the polymer flocculant solution when treating high turbidity raw water, and the small flow rate pump can be used to send the polymer flocculant solution when treating low turbidity raw water. It is preferable to use a large flow rate pump to discharge the wastewater in a short time. In addition, when using a polymer flocculant solution in a wastewater treatment system, a larger amount is used than in a water purification treatment system, so it is preferable to use a large flow rate pump. A valve such as a three-way valve may be used to switch the pump. The control unit 220 can operate the pump 182 so that the polymer flocculant solution 114 is supplied to the flocculation tank 191 according to the determined injection flow rate F1.

[0050] In one embodiment, the control device 200 controls the supply system 100 to prepare a new polymer flocculant solution 114 only when it is determined that there is no polymer flocculant solution 114 remaining in the dissolution storage tank 110. In addition, in one embodiment, when it is determined that there is polymer flocculant solution 114 remaining in the dissolution storage tank 110, the control device 200 controls the supply system 100 to discard the polymer flocculant solution 114 remaining in the dissolution storage tank 110 and then prepare a new polymer flocculant solution 114.

[0051] The determination that no polymer flocculant solution 114 remains in the dissolution storage tank 110 can be made, for example, by the control device 200 receiving measurement results from a water level measuring device (not shown) such as a level gauge or level switch installed in the dissolution storage tank 110, and the calculation unit 210 of the control device 200 determining that the water level satisfies a predetermined water level standard stored in the memory unit 230 (e.g., the water level drops to a level where it is no longer possible to measure using at least one of the concentration meter 150 and the transparency meter 160, i.e., the water level drops below the level of at least one of these measuring units).

[0052] (B. Preparation and supply of polymer flocculant solution with changed concentration) In one embodiment, the control device 200 can control the supply system 100 to prepare the polymer flocculant solution 114 with a changed concentration by using the polymer flocculant solution 114 remaining in the dissolution reservoir 110. The criteria for determining whether to prepare a new polymer flocculant solution 114 or to prepare the polymer flocculant solution 114 with a changed concentration can be determined in advance. In one embodiment, the control device 200 controls the supply system 100 to prepare the polymer flocculant solution 114 with a changed concentration when it is determined that the polymer flocculant solution 114 remains in the dissolution reservoir 110.

[0053] The determination of whether polymer flocculant solution 114 remains in the dissolution storage tank 110 can be made, for example, by the control device 200 receiving measurement results from a water level measuring device (not shown) such as a level gauge or level switch installed in the dissolution storage tank 110, and the calculation unit 210 of the control device 200 determining that the water level satisfies a predetermined water level standard stored in the memory unit 230 (e.g., a water level that can be measured by the concentration meter 150 and the transparency meter 160, i.e., a water level that is higher than these measuring units).

[0054] When preparing the polymer flocculant solution 114 with a changed concentration, once the target dissolution concentration X1 is determined, the calculation unit 210 of the control device 200 can further compare X1 and X2 based on the dissolution concentration X2 of the polymer flocculant in the existing polymer flocculant solution. The dissolution concentration X2 may be the result measured by the concentration meter 150, or the target dissolution concentration (= the dissolution concentration X1 at the time of the previous preparation) when the existing polymer flocculant solution was prepared may be regarded as the dissolution concentration X2. In one embodiment, the dissolution concentration X1 at the time of the previous preparation may be stored in the memory unit 230, and the calculation unit 210 can compare the dissolution concentration X1 at the time of the previous preparation stored in the memory unit 230 with the target dissolution concentration X1 this time. However, since the dissolution concentration of the polymer flocculant in the polymer flocculant solution may change over time due to deterioration or the like, it is preferable to measure it using the concentration meter 150. Also, the deterioration may be diagnosed by a transparency meter 160 or the like, and the target concentration when the existing polymer flocculant solution is prepared may be regarded as the dissolved concentration X2 only when the deterioration degree is diagnosed to be within the allowable range. The deterioration diagnosis may be performed periodically, or may be performed whenever it becomes necessary to prepare the polymer flocculant solution 114 with a changed concentration. There is no particular restriction on the timing of measuring the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution by the concentration meter 150, but it may be, for example, the same time as the timing of measuring a predetermined condition of the flocculation tank 191, after the condition measurement, or before the condition measurement. Furthermore, the dissolved concentration X2 may be measured periodically, and the most recent measured value may be used as the dissolved concentration X2. Among them, the timing of measuring the dissolved concentration X2 is preferably after the condition measurement. The timing of measuring the dissolved concentration X2 is preferably within 5 minutes after the condition measurement, and more preferably immediately.

[0055] As a result of comparing X1 and X2, if X1>X2, the dissolution concentration X2 of the polymer flocculant in the existing polymer flocculant solution is lower than the target dissolution concentration X1, and therefore needs to be increased. Therefore, in one embodiment, when X1>X2, the calculation unit 210 can determine the amount of polymer flocculant 125 required to obtain the polymer flocculant solution 114 of the dissolution concentration X1, taking into consideration the injection flow rate F1 of the polymer flocculant solution 114 as necessary, based on the dissolution concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191, the dissolution concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114, and the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110, in the case of X1>X2. The control unit 220 can control the amount of polymer flocculant 125 supplied from the polymer flocculant supply device 120 to the dissolution storage tank 110 according to the determination of the calculation unit 210.

[0056] The polymer flocculant 125 supplied to the dissolution storage tank 110 is dissolved while being stirred with the existing polymer flocculant solution 114 by the stirrer 140 under stirring conditions such as a predetermined rotation speed and stirring time, and a polymer flocculant solution with a changed concentration is prepared. The stirring conditions such as the rotation speed and stirring time of the stirrer 140 may be set by an operator via the input unit 240, may be stored in advance in the memory unit 230, or may be automatically set by the calculation unit 210 according to the amount of the polymer flocculant 125 supplied. The stirrer 140 can be operated under the set stirring conditions based on a command from the control unit 220.

[0057] As the concentration meter 150 for measuring the dissolution concentration X2 of the polymer flocculant in the polymer flocculant solution, from the viewpoint of speed and simplicity, an instrument for measuring information correlated with the dissolution concentration X2, for example, a torque meter or viscometer (not shown, but can be installed independently of the agitator 140) that can be installed at the position of the motor unit of the agitator 140, can be adopted. By experimentally determining the relationship between the dissolution concentration X2 from the information measured by these instruments in advance, the dissolution concentration X2 can be indirectly measured from the information measured by the instruments. For example, if a database such as a spreadsheet in which the information measured by the instruments and the dissolution concentration X2 are associated and stored, a machine learning model that calculates the dissolution concentration X2 according to the information measured by the instruments, or an algorithm such as a formula that can calculate the dissolution concentration X2 according to the information measured by the instruments is stored in advance in the storage unit 230, the calculation unit 210 can calculate the dissolution concentration X2 based on the information measured by the instruments and the above database, machine learning model, or algorithm. Since the relationship between the information measured by the meter and the dissolved concentration X2 varies depending on the type of polymer flocculant, it is preferable to obtain the relationship for each type of polymer flocculant in order to improve the measurement accuracy.

[0058] The amount of existing polymer flocculant solution 114 in the dissolution storage tank 110 can be measured, for example, based on the measurement results of a water level measuring device (not shown) such as a level gauge or level switch installed in the dissolution storage tank 110 and the bottom area of ​​the dissolution storage tank 110.

[0059] If the amount of the polymer flocculant solution 114 already in the dissolution storage tank 110 is E, and the amount of the polymer flocculant 125 required to obtain the polymer flocculant solution 114 with a dissolution concentration of X1 is Q, the calculation unit 210 can determine Q by, for example, calculating Q=E(X1-X2). Other calculation formulas may also be used.

[0060] If the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110 is small, even if Q is added, it may not be possible to secure a sufficient injection time (e.g., 24 hours or more) at the injection flow rate F1 of the polymer flocculant solution 114 required for the flocculation tank 191. In that case, the control device 200 may calculate the amount of aqueous solvent to be additionally supplied from the first solvent supply line 130 to the dissolution storage tank 110 and the amount of polymer flocculant 125 to be additionally supplied from the polymer flocculant supply device 120 to the dissolution storage tank 110, and control the equipment required to additionally prepare the polymer flocculant solution 114 with the required dissolution concentration X1 based on the calculation result. As an example, the control device 200 can additionally prepare the polymer flocculant solution 114 so that the dissolution storage tank 110 is full.

[0061] The polymer flocculant 125 supplied to the dissolution storage tank 110 is dissolved while being stirred with the existing polymer flocculant solution 114 and the added aqueous solvent under stirring conditions such as a predetermined rotation speed and stirring time by the stirrer 140, and a polymer flocculant solution with a changed concentration is prepared. The stirring conditions such as the rotation speed and stirring time of the stirrer 140 may be set by an operator via the input unit 240, may be stored in advance in the memory unit 230, or may be automatically set by the calculation unit 210 according to the amount of the polymer flocculant 125 supplied. The stirrer 140 can be operated under the set stirring conditions based on a command from the control unit 220.

[0062] The control device 200 is capable of operating the pump 182 and the flow path switching valves 131b, 131c, and 131e so that the concentration-adjusted polymer flocculant solution 114 in the dissolution storage tank 110 is injected from the outlet 112 of the dissolution storage tank 110 through the injection line 181 to the injection point 185A of the polymer flocculant solution 114.

[0063] Alternatively, even if X1 > X2, if the difference or ratio between the two is small, the concentration of the polymer flocculant in the existing polymer flocculant solution can be left unchanged and the existing polymer flocculant solution can be used as it is. Therefore, a polymer flocculant solution with a changed concentration may be prepared only when X1 > X2 and the difference or ratio between the two satisfies a predetermined condition. Further, when X1 > X2, regardless of the magnitude of the difference or ratio between the two, the concentration of the polymer flocculant in the existing polymer flocculant solution can be left unchanged and the existing polymer flocculant solution can be used as it is. Since the operation of increasing the concentration of the polymer flocculant in the polymer flocculant solution takes time, the rapidity can be increased by adjusting the injection flow rate F1 to supply the required polymer flocculant without adjusting the concentration. However, the injection flow rate F1 needs to be within the discharge amount range of the pump 182.

[0064] On the other hand, as a result of comparing X1 and X2, when X1 < X2, the dissolved concentration X2 of the polymer flocculant in the existing polymer flocculant solution is higher than the target dissolved concentration X1, so it is necessary to lower (dilute) it. In one embodiment, the calculation unit 210 can determine the amount of the aqueous solvent required to obtain the polymer flocculant solution 114 with the dissolved concentration X1 when X1 < X2. The control unit 220 can control the amount of the aqueous solvent supplied from the first solvent supply line 130 to the dissolution storage tank 110 according to the determination of the calculation unit 210.

[0065] The amount of the aqueous solvent required to obtain the polymer flocculant solution 114 with the dissolved concentration X1 can be determined by the calculation unit 210 based on the dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191, the dissolved concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114, and the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110, taking into account the injection flow rate F1 of the polymer flocculant solution 114 as necessary.

[0066] If the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110 is W, and the amount of the aqueous solvent (e.g., dilution water) required to obtain the polymer flocculant solution 114 with a dissolution concentration of X1 is R, the calculation unit 210 can determine R by, for example, calculating R=W(X2 / X1-1). Other calculation formulas may be used.

[0067] If the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110 is small, even if R is added, it may not be possible to secure a sufficient injection time (e.g., 24 hours or more) at the injection flow rate F1 of the polymer flocculant solution 114 required for the flocculation tank 191. In that case, the control device 200 may calculate the amount of aqueous solvent to be additionally supplied from the first solvent supply line 130 to the dissolution storage tank 110 and the amount of polymer flocculant 125 to be additionally supplied from the polymer flocculant supply device 120 to the dissolution storage tank 110, and control the equipment required to additionally prepare the polymer flocculant solution 114 with the required dissolution concentration X1 based on the calculation result. As an example, the control device 200 can additionally prepare the polymer flocculant solution 114 so that the dissolution storage tank 110 is full.

[0068] The control unit 220 can operate the pump 182 so that the polymer flocculant solution 114 is supplied to the flocculation tank 191 according to the determined injection flow rate. It is preferable to use a metering pump capable of supplying a fixed amount as the pump 182. Although one pump may be used, a pump capable of supplying a relatively large flow rate and a pump capable of supplying a relatively small flow rate may be provided in parallel. For example, a large flow rate pump can be used to send the polymer flocculant solution when treating high turbidity raw water, and a small flow rate pump can be used to send the polymer flocculant solution when treating low turbidity raw water. It is preferable to use a large flow rate pump to discharge the wastewater in a short time. In addition, when using a polymer flocculant solution in a wastewater treatment system, a larger amount is used than in a water purification system, so it is preferable to use a large flow rate pump. A valve such as a three-way valve can be used to switch between pumps.

[0069] In the above-described embodiment, when X1 < X2, a polymer flocculant solution with a dissolved concentration changed to X1 is prepared in the dissolution storage tank 110. However, it is also possible to prepare the polymer flocculant solution with a dissolved concentration changed to X1 outside the dissolution storage tank 110. For example, in one embodiment, the supply system 100 is a second solvent supply line 132 that branches from the first solvent supply line 130 via the first flow path switching valve 131a or is independent of the first solvent supply line 130, and joins the injection line 181 via the second flow path switching valve 131b, and can have a mixing device 193 such as a line mixer installed in the injection line 181 on the downstream side of the second flow path switching valve 131b. The second flow path switching valve 131b can be provided, for example, between the outlet 112 of the dissolution storage tank 110 and the pump 182. As the second flow path switching valve 131b, for example, a three-way valve can be used. The supply system 100 may have a bypass line (not shown) for the case where it is not necessary to pass through the mixing device 193. In that case, a flow path switching valve (not shown) for making it possible to switch between the path passing through the mixing device 193 and the path passing through the bypass line can be further provided. As for the flow path switching valve, an electric drive valve can be used in the same manner as other flow path switching valves, and the switching can be configured to be executable by the control unit 220.

[0070] In the illustrated embodiment, the second solvent supply line 132 branches from the first solvent supply line 130 via the first flow path switching valve 131a, but the second solvent supply line 132 may be provided independently of the first solvent supply line 130. Also, in the illustrated embodiment, the second solvent supply line 132 joins the injection line 181 via the second flow path switching valve 131b, but the second solvent supply line 132 may be directly connected to the mixing device 193.

[0071] In an embodiment where the supply system 100 has a mixing device 193, when X1 < X2, the calculation unit 210 can determine the ratio of the existing polymer flocculant solution and the aqueous solvent such that a polymer flocculant solution 114 with a dissolution concentration of X1 is obtained. Further, the control unit 220 can control the flow rate of the aqueous solvent supplied to the injection line 181 via the second solvent supply line 132 and the flow rate of the existing polymer flocculant solution supplied from the dissolution storage tank 110 to the injection line 181 so as to be in the ratio according to the determination of the calculation unit 210. Further, the control unit 220 supplies the aqueous solvent to the injection line 181 via the second solvent supply line 132 and simultaneously supplies the existing polymer flocculant solution 114 from the dissolution storage tank 110 to the injection line 181, and mixes the two by the mixing device 193 in the injection line 181 to prepare a polymer flocculant solution 114 whose concentration is changed to X1, and the supply system 100 such as the operation of the flow path switching valve that requires flow path switching, the operation of the pump 182, and the operation of the flow rate control valve for the aqueous solvent can be operated so that the concentration-changed polymer flocculant solution 114 is supplied to the flocculation tank 191. According to this embodiment, there is an advantage that the concentration of the polymer flocculant solution 114 can be quickly changed while continuing the supply of the polymer flocculant solution 114 to the flocculation tank 191.

[0072] If the dissolution concentration X2 of the polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 110 is adjusted (set) high in advance and the case where X1 > X2 is excluded, then always X1 = X2 or X1 < X2. In this case, the existing polymer flocculant solution in the dissolution storage tank 110 is either used as it is or diluted and used. Since the dilution operation can be performed more quickly than the operation of increasing the concentration, it can be quickly adjusted to the target dissolution concentration X1.

[0073] As another method, even if X1 < X2, when the difference or ratio between the two is small, the concentration of the polymer flocculant in the existing polymer flocculant solution may not be changed and the existing polymer flocculant solution may be used as it is. Therefore, a polymer flocculant solution with a changed concentration may be prepared only when X1 < X2 and the difference or ratio between the two satisfies a predetermined condition.

[0074] In order to monitor the change over time in the measurement results by the measuring device 192 that measures the condition of the coagulation tank 191, it is preferable that the control device 200 can issue a command to the measuring device 192 to measure one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulation flocs in the coagulation tank 191 at a plurality of different predetermined times. In addition to the measuring devices for measuring the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulation flocs in the coagulation tank 191, other measuring devices such as a water thermometer, a hygrometer, and a density meter can be installed in the coagulation tank 191. The results of one or more of these measurements may be reflected in the preparation conditions and / or supply conditions of the polymer coagulant solution 114.

[0075] The multiple different predetermined periods (measurement schedule) may be appropriately set according to the empirically found rate of change in the conditions of the coagulation tank 191, and may be measured periodically, for example, by setting the measurement date and time every hour, every day, every week, or every month, or may be measured continuously. In order to easily respond to sudden changes in the conditions, it is preferable to measure at least once every hour.

[0076] When preparing a new polymer flocculant solution 114, it is preferable to measure immediately before preparation (for example, 1 to 10 minutes before the polymer flocculant 125 is supplied from the supply port 126 to the dissolution storage tank 110). When using an existing polymer flocculant solution 114, it is preferable to measure immediately before use (for example, 1 to 10 minutes before starting the pump 182 to inject the polymer flocculant solution 114 in the dissolution storage tank 110 to the injection point 185A). The predetermined different timings can be set via the input unit 240 of the control device 200.

[0077] The measurement schedules set via the input unit 240 are stored in the memory unit 230 of the control device 200. The control unit 220 can operate the measuring device 192 and perform predetermined measurements based on the measurement schedules stored in the memory unit 230. The measurement data can be stored in the memory unit 230 in association with the measurement date and time. Such a data storage function can be realized by using, for example, a data logger.

[0078] (C. Disposal of polymer flocculant solution, cleaning of injection lines, etc.) In one embodiment, the supply system 100 includes a second solvent supply line 132 that branches off from the first solvent supply line 130 via a first flow path switching valve 131a and joins the injection line 181 between the outlet 112 of the dissolution reservoir 110 and the pump 182 via a second flow path switching valve 131b; a branch line 186 branching off from the injection line 181 via a third flow path switching valve 131c between the pump 182 and an injection point 185A of the polymer flocculant solution 114; a return line 188 that branches off from the branch line 186 via a fourth flow path switching valve 131d and is connected to the dissolution storage tank 110; a waste line 189 branched from the branch line 186 via a fourth flow path switching valve 131d and connected to a wastewater treatment facility 190; Equipped with.

[0079] In one embodiment, the control unit 220 of the control device 200 can execute a disposal operation of the polymer flocculant solution 114 by operating a flow path switching valve that needs to switch the flow path among the second flow path switching valves 131b so that the polymer flocculant solution 114 in the dissolution storage tank 110 is supplied to the wastewater treatment facility 190 through the injection line 181, the branch line 186, and the disposal line 189, and starting the pump 182. Since the disposal operation involves a valve switching operation, it is preferable to start the operation from a state in which the pump 182 is stopped. Therefore, in one embodiment, when the pump 182 is operating, the control unit 220 can stop the pump 182 and then execute the disposal operation. The operator may issue a command to the control unit 220 via the input unit 240. The disposal command may be a command to immediately execute the disposal operation, or a command to execute the disposal operation at a predetermined date and time. The contents of the command can be appropriately stored in the memory unit 230. Also, the system may be programmed in advance to automatically execute the disposal operation when a predetermined disposal condition (e.g., a predetermined storage period has elapsed, the quality of the polymer flocculant solution has deteriorated, etc.) is met. The deterioration in quality of the polymer flocculant solution 114 may be caused by factors such as decomposition by sodium hypochlorite or generation of fine particles by Ca or the like, and white turbidity is often observed along with the quality deterioration. Therefore, for example, it can be determined that the quality deterioration has occurred when the result of measuring the transparency of the polymer flocculant solution 114 using a transparency meter 160 satisfies a predetermined condition.

[0080] The disposal operation may be terminated when a predetermined time has elapsed. The disposal operation may also be terminated when the height of the polymer flocculant solution in the dissolution storage tank 110 is measured by a water level measuring device (not shown) such as a level gauge or a level switch, and the height of the polymer flocculant solution in the dissolution storage tank 110 drops to a predetermined value. Other conditions may be set as the termination condition for the disposal operation.

[0081] The injection line 181 may be washed when there is no need to supply the polymer flocculant solution 114 to the injection point 185A and the pump 182 is stopped. The injection line 181 may also be washed after the polymer flocculant solution 114 is discarded. Washing the injection line 181 is important because it prevents residual polymer flocculant solution in the piping from being injected into the injection line 181 when injection is resumed next time, making it possible to maintain water quality at all times.

[0082] Therefore, in one embodiment, the control unit 220 can perform flushing by operating a flow path switching valve that needs to switch the flow path among the first flow path switching valve 131a, the second flow path switching valve 131b, the third flow path switching valve 131c, and the fourth flow path switching valve 131d so that the aqueous solvent from the first solvent supply line 130 is supplied to the dissolution storage tank 110 through the second solvent supply line 132, the injection line 181, the branch line 186, and the return line 188, and starting the pump 182. When flushing is performed, the aqueous solvent flows through the injection line 181, so that the part of the injection line 181 including the pump 182 can be washed. In addition, the return line 188 and the branch line 186 connected to the waste line 189 can be washed.

[0083] In one embodiment, the control unit 220 can further execute flushing by operating a flow path switching valve that needs to switch the flow path among the first flow path switching valve 131a, the second flow path switching valve 131b, the third flow path switching valve 131c, and the fifth flow path switching valve 131e so that the aqueous solvent from the first solvent supply line 130 is supplied to the injection point 185A through the second solvent supply line 132 and the injection line 181, and activating the pump 182. This can also clean the part of the injection line 181 from the third flow path switching valve 131c to the injection point 185A that cannot be cleaned by the above flushing. Since the flushing involves a valve switching operation, it is preferable to start the flushing from a state in which the pump 182 is stopped. Therefore, in one embodiment, when the pump 182 is operating, the control unit 220 can execute flushing after stopping the pump 182.

[0084] When the aqueous solvent has pressure, such as tap water, this pressure can be utilized to flush the inside of the piping of the injection line 181 (for example, by connecting the second solvent supply line 132 to the downstream side of the pump 182). However, taking into consideration the flushing inside the pump 182, it is preferable to connect the second solvent supply line 132 to the upstream side of the pump 182.

[0085] Flushing may be configured to be performed automatically after the polymer flocculant solution 114 is discarded. Alternatively, for example, the control unit 220 may be configured to perform flushing when an operator issues a flushing command via the input unit 240. The flushing command may be a command to perform flushing immediately, or a command to perform flushing at a predetermined date and time. The contents of the command may be stored in the memory unit 230 as appropriate.

[0086] The flushing may be terminated when a predetermined time has elapsed. The flushing may also be terminated under the condition that the pipe to be flushed is washed with a water-based solvent in a volume, for example, 2 to 4 times, typically 3 times the volume of the pipe to be flushed. Other conditions may be set as the condition for terminating the flushing.

[0087] After flushing, the above-mentioned disposal operation may be performed again to discharge the aqueous solvent remaining in the dissolution storage tank 110. In addition, after flushing, the aqueous solvent remaining in the dissolution storage tank 110 may be reused for the next preparation of the polymer flocculant solution 114. Reuse contributes to energy saving and cost reduction.

[0088] After the disposal operation and flushing of the polymer flocculant solution 114, a new polymer flocculant solution 114 can be prepared in the dissolution storage tank 110. In one embodiment, the control unit 220 controls the first flow path switching valve 131a and a flow control valve (not shown) so that a predetermined amount of the aqueous solvent from the first solvent supply line 130 is supplied into the dissolution storage tank 110, and can control the polymer flocculant supply device 120 so that a predetermined amount of the polymer flocculant 125 is supplied into the dissolution storage tank 110. The control unit 220 can also control the agitator 140. In one embodiment, when the pump 182 is in operation, the control unit 220 can prepare the polymer flocculant solution 114 after stopping the pump 182.

[0089] On the other hand, if the supply system 100 is continued to be used, the seepage meter 160 also becomes dirty over time, and the measurement accuracy of the dissolution concentration decreases. For this reason, it is preferable to clean the seepage meter 160 as well. Therefore, in one embodiment, the supply system 100 includes a cleaning line 133 that branches off from the first solvent supply line 130 via the first flow path switching valve 131a, and is provided with the cleaning line 133 for spraying the aqueous solvent from its outlet 134 toward the seepage meter 160. For this reason, in one embodiment, the control unit 220 can control the first flow path switching valve 131a so that the aqueous solvent from the first solvent supply line 130 flows out of the outlet 134 through the cleaning line 133. The seepage meter 160 can be cleaned by spraying the aqueous solvent from the outlet 134 of the cleaning line 133 toward the seepage meter 160. There is no particular limitation on the method of spraying the aqueous solvent toward the seepage meter 160, and a spraying method, a pouring method, or the like may be appropriately selected.

[0090] There is no particular restriction on the timing of cleaning the see-through meter 160, but it is preferable to do so after it is determined that the polymer flocculant solution 114 in the dissolution storage tank 110 is to be discarded. For example, cleaning can be performed after the determination, before, during, or after the discarding operation of the polymer flocculant solution 114. Cleaning can also be performed immediately before preparing a new polymer flocculant solution 114 (for example, 1 to 10 minutes before the polymer flocculant 125 is supplied from the supply port 126 to the dissolution storage tank 110). In addition, for example, the control unit 220 can be configured to perform a cleaning operation on the see-through meter 160 by an operator issuing a cleaning command for the see-through meter 160 via the input unit 240. The cleaning command can be a command to immediately perform a cleaning operation, or a command to perform a cleaning operation at a predetermined date and time. The contents of the command can be appropriately stored in the memory unit 230.

[0091] The cleaning of the transparency meter 160 may be ended when a predetermined time has elapsed. The cleaning of the transparency meter 160 may also be ended on the condition that a predetermined volume, for example, 1 to 10 L of aqueous solvent is supplied. The switch of the transparency meter 160 may be left on, and the end condition may be when the indicated value of the transparency meter 160 during cleaning becomes stable. Other conditions may be set as the end condition for cleaning of the transparency meter 160.

[0092] Two or more supply systems 100 may be installed in parallel. This allows one supply system 100 to operate when changing the concentration of the polymer flocculant solution in the supply system 100, performing maintenance, flushing, or replacing the polymer flocculant solution, and therefore reduces or eliminates the time when the supply system 100 cannot be used.

[0093] The supply system 100 may branch the injection line 181 so that the polymer flocculant solution can be supplied to a plurality of flocculation tanks. For example, as shown in Fig. 1, a branch line 181-2 to another flocculation tank 191-2 can be provided via a fifth flow path switching valve 131e. For example, when the flocculation tank 191 is a flocculation sedimentation treatment facility in a water purification facility, the other flocculation tank 191-2 may be a rapid sand filter.

[0094] Also, although not shown, the injection line 181 may be provided independently from the outlet 112 of the dissolution storage tank 110 for each coagulation tank without branching the injection line 181. For example, the concentration range of the polymer coagulant tends to be different between coagulation sedimentation and filtration, and generally the concentration is lower in filtration. For this reason, a line that directly supplies the polymer coagulant and a line that supplies it after dilution are separately provided, so that polymer coagulants of different concentration ranges can be supplied from one storage tank for each process, enabling efficient operation.

[0095] <2. How to supply polymer flocculant solution> According to one embodiment of the present invention, a method for supplying a polymer flocculant solution 114 is provided. The method for supplying a polymer flocculant solution 114 can be performed without using the supply system 100 for the polymer flocculant solution 114 according to one embodiment of the present invention, for example, by a human being, but can be preferably performed by using the supply system 100. Therefore, in the following, for ease of understanding, the method for supplying a polymer flocculant solution 114 will be described with reference to the reference numerals given to the supply system 100 shown in FIG. 1.

[0096] (A. Preparation and supply of new polymer flocculant solution) In one embodiment, the method for supplying the polymer flocculant solution 114 includes the following steps: A step A1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulation flocs in the coagulation tank 191; A step A2 of determining a dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result in the step A1; A process A3 of supplying the aqueous solvent and the polymer flocculant 125 to the dissolution storage tank 110 in a ratio such that a polymer flocculant solution 114 having a dissolution concentration X1 is obtained; A step A4 of dissolving the polymer flocculant 125 in the dissolution storage tank 110 in the aqueous solvent while stirring to prepare a polymer flocculant solution 114; A step A5 of supplying the polymer flocculant solution 114 prepared in the step A4 to a flocculation tank 191; Includes.

[0097] The above-mentioned method for supplying the polymer flocculant solution 114 can be suitably used when the polymer flocculant solution 114 is newly prepared and supplied. FIG. 2 shows an example of a flow chart of the method for supplying the polymer flocculant solution 114 according to an embodiment of the present invention when the polymer flocculant solution 114 is newly prepared and supplied, using the supply system 100 for the polymer flocculant solution 114 according to an embodiment of the present invention. First, in response to a command from the control unit 220 of the control device 200, the measuring device 192 measures one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulated flocs in the coagulation tank 191 (S101). The measurement result is stored in the memory unit 230 of the control device 200 together with the measurement date and time.

[0098] Next, the calculation unit 210 of the control device 200 determines the dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result by the measurement device 192 (S102). At this time, the calculation unit 210 may further determine the injection flow rate F1 of the polymer flocculant solution 114 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result by the measurement device 192.

[0099] Next, when the dissolution concentration X1 is determined, the control device 200 takes into consideration the injection flow rate F1 as necessary, supplies the aqueous solvent from the first solvent supply line 130 to the dissolution storage tank 110 at a ratio that obtains the polymer flocculant solution 114 of the dissolution concentration X1, and supplies the polymer flocculant 125 from the polymer flocculant supply device 120 to the dissolution storage tank 110 (S103). S103 may be executed only when it is determined that the polymer flocculant solution 114 does not remain in the dissolution storage tank 110. In addition, when the control device 200 determines that the polymer flocculant solution 114 remains in the dissolution storage tank 110, it may execute S103 after discarding the polymer flocculant solution 114 remaining in the dissolution storage tank 110. In addition, when the control device 200 determines that the polymer flocculant solution 114 remains in the dissolution storage tank 110, it may prepare the polymer flocculant solution 114 whose concentration has been changed according to the procedure described below using the existing polymer flocculant solution 114.

[0100] When the aqueous solvent and the polymer flocculant 125 are introduced into the dissolution storage tank 110, the polymer flocculant 125 dissolves in the aqueous solvent, and the polymer flocculant solution 114 is prepared (S104). The control device 200 can determine the stirring conditions, such as the number of revolutions and the stirring time of the stirrer, based on the dissolution concentration X1, and can operate the stirrer 140 under those conditions. The method of determining the stirring conditions, such as the number of revolutions and the stirring time of the stirrer, based on the dissolution concentration X1 is as described above.

[0101] After the stirring is completed, the control unit 220 operates the flow path switching valves 131b, 131c, and 131e that need to be switched in addition to the pump 182, and supplies the polymer flocculant solution 114 in the dissolution storage tank 110 to the injection point 185A of the polymer flocculant solution 114 in the coagulation tank 191 (S105). In this specification, the injection point of the polymer flocculant solution in the coagulation tank includes a case where the injection point is provided in the coagulation tank, as well as a case where the injection point is provided in the pipe upstream of the coagulation tank and in the pipe downstream of the treatment process immediately before the coagulation tank. The injection flow rate F1 of the polymer flocculant solution 114 supplied to the coagulation tank 191 can be determined by the method described above. The control unit 220 can operate the pump 182 so that the polymer flocculant solution 114 is supplied to the coagulation tank 191 according to the determined injection flow rate F1.

[0102] (B. Preparation and supply of polymer flocculant solution with changed concentration) In one embodiment, the method for supplying the polymer flocculant solution 114 includes the steps of: A step B1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank 191, the properties of the water to be treated flowing into the coagulation tank 191, and the coagulation state of the coagulation flocs in the coagulation tank 191; A step B2 of determining a dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement result in the step B1; A step B3 of determining a dissolved concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114 in the dissolution storage tank 110; A step B4 of comparing X1 and X2; When X1>X2, a step B5 of determining the amount of polymer flocculant 125 required to obtain the polymer flocculant solution 114 having a dissolution concentration X1 based on the dissolution concentration X1, the dissolution concentration X2, and the amount of the polymer flocculant solution 114 already in the dissolution storage tank 110; Step B6 of supplying the amount of polymer flocculant 125 determined in step B5 to the dissolution storage tank 110; A process B7 in which the polymer flocculant 125 supplied to the dissolution storage tank 110 is dissolved in the existing polymer flocculant solution 114 while stirring to prepare a polymer flocculant solution 114 with a changed concentration; Step B8 of supplying the polymer flocculant solution 114 with a changed concentration prepared in Project B7 to the flocculation tank 191, is included.

[0103] Also, in one embodiment, the method of supplying the polymer flocculant solution 114 is Step C1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank 191, the properties of the water to be treated flowing into the flocculation tank 191, and the flocculation status of the flocculated flocs in the flocculation tank 191; Step C2 of determining the dissolution concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement results in Step C1; Step C3 of determining the dissolution concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114 in the dissolution storage tank 110; Step C4 of comparing X1 and X2; When X1 < X2, based on the dissolution concentration X1, the dissolution concentration X2, and the amount of the existing polymer flocculant solution 114 in the dissolution storage tank, Step C5 of determining the amount of the aqueous solvent required to obtain the polymer flocculant solution 114 with the dissolution concentration X1; Step C6 of supplying the amount of the aqueous solvent determined in Step C5 to the dissolution storage tank 110; Step C7 of stirring the aqueous solvent supplied to the dissolution storage tank 110 together with the existing polymer flocculant solution 114 to prepare a polymer flocculant solution 114 with a changed concentration; Step C8 of supplying the polymer flocculant solution 114 with a changed concentration prepared in Step C7 to the flocculation tank 191; is included.

[0104] Also, in another embodiment, the method of supplying the polymer flocculant solution 114 is Step D1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank 191, the properties of the water to be treated flowing into the flocculation tank 191, and the flocculation status of the flocculated flocs in the flocculation tank 191; Step D2 of determining the dissolution concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based at least on the measurement results in Project D1; Step D3 of determining the dissolution concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114 in the dissolution storage tank 110; Step D4 of comparing X1 and X2; When X1 < X2, the aqueous solvent is supplied to the injection line 181 at a flow rate ratio at which the polymer flocculant solution 114 with the dissolution concentration X1 is obtained, and at the same time, the existing polymer flocculant solution 114 is supplied from the dissolution storage tank 110 to the injection line 181, and the two are mixed by the mixing device 193 in the injection line 181 to prepare a polymer flocculant solution 114 changed to the dissolution concentration X1. Step D5; Step D6 of supplying the polymer flocculant solution 114 with the changed concentration to the flocculation tank 191 via the injection line 181; including.

[0105] The above method for supplying the polymer flocculant solution 114 can be preferably used when an existing polymer flocculant solution is used to prepare and supply a polymer flocculant solution with a changed concentration. FIG. 3 shows a method for supplying the polymer flocculant solution 114 according to an embodiment of the present invention when preparing and supplying a polymer flocculant solution with a changed concentration, and a flowchart example when using the supply system 100 of the polymer flocculant solution 114 according to an embodiment of the present invention. First, according to a command from the control unit 220 of the control device 200, the measuring device 192 measures one or more conditions selected from the flow rate of the water to be treated flowing into the flocculation tank 191, the properties of the water to be treated flowing into the flocculation tank 191, and the flocculation status of the flocculant flocs in the flocculation tank 191 (S201). The measurement results are stored in the storage unit 230 of the control device 200 together with the measurement date and time.

[0106] Next, the calculation unit 210 of the control device 200 determines the dissolved concentration X1 of the polymer flocculant 125 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based on at least the measurement result by the measurement device 192 (S202). At this time, the calculation unit 210 may further determine the injection flow rate F1 of the polymer flocculant solution 114 in the polymer flocculant solution 114 to be supplied to the flocculation tank 191 based on at least the measurement result by the measurement device 192.

[0107] Next, when the calculation unit 210 judges that the polymer flocculant solution 114 remains in the dissolution storage tank 110, the concentration meter 150 measures the dissolution concentration X2 of the polymer flocculant 125 in the existing polymer flocculant solution 114 (S203). Note that the timing for measuring the dissolution concentration X2 is not limited to this. Also, as described above, the concentration meter 150 may not be used, and the dissolution concentration X1 at the time of the previous preparation may be regarded as the dissolution concentration X2.

[0108] Next, the calculation unit 210 compares X1 and X2 (S204). If the result of comparing X1 and X2 is X1>X2, the calculation unit 210 determines the amount of polymer flocculant 125 required to obtain the polymer flocculant solution 114 with the dissolution concentration X1 based on the dissolution concentration X1, the dissolution concentration X2, and the amount of the existing polymer flocculant solution 114 in the dissolution storage tank 110 (S205). Next, the control unit 220 operates the polymer flocculant supply device 120 to supply the determined amount of polymer flocculant 125 to the dissolution storage tank 110 (S206). The control unit 220 operates the agitator 140 to dissolve the polymer flocculant 125 supplied to the dissolution storage tank 110 in the existing polymer flocculant solution 114 while stirring, thereby preparing the polymer flocculant solution 114 with the changed concentration (S207).

[0109] After the stirring is completed, the control unit 220 operates the pump 182 and the flow path switching valves 131b, 131c, and 131e to supply the polymer flocculant solution 114 in the dissolution storage tank 110 to the injection point 185A of the polymer flocculant solution 114 in the flocculation tank 191 (S208).

[0110] On the one hand, as a result of comparing X1 and X2, when X1 < X2, the arithmetic unit 210 determines the amount of the aqueous solvent required to obtain the polymer flocculant solution 114 with the dissolution concentration X1 (S209). Next, the control unit 220 supplies the aqueous solvent from the first solvent supply line 130 to the dissolution storage tank 110 (S210).

[0111] The control unit 220 operates the stirrer 140 to stir the aqueous solvent supplied to the dissolution storage tank 110 together with the existing polymer flocculant solution 114, and prepares the polymer flocculant solution 114 with the changed concentration (S211).

[0112] After the stirring is completed, the control unit 220, in addition to the pump 182, operates the flow path switching valves among the flow path switching valves 131b, 131c, and 131e that need to be switched, and supplies the polymer flocculant solution 114 to the injection point 185A of the polymer flocculant solution 114 in the coagulation tank 191 (S212).

[0113] As a result of comparing X1 and X2, when X1 = X2, the control unit 220, in addition to the pump 182, operates the flow path switching valves among the flow path switching valves 131b, 131c, and 131e that need to be switched, and supplies the existing polymer flocculant solution 114 in the dissolution storage tank 110 to the injection point 185A of the polymer flocculant solution 114 in the coagulation tank 191 (S213). Here, X1 = X2 includes not only the case where X1 and X2 are completely equal, but also the case where the difference or ratio between the two is within a preset allowable range. Therefore, when the difference or ratio between the two is within the preset allowable range, it may be regarded as X1 = X2, and the existing polymer flocculant solution 114 in the dissolution storage tank 110 may be used as it is. Thereby, the polymer flocculant solution 114 can be quickly supplied to the coagulation tank 191 when necessary.

Explanation of Signs

[0114] 100: Supply System 110: Dissolution Storage Tank 112: Outlet 114: Polymer Flocculant Solution 120: Polymer Flocculant Supply Device 122: Polymer Flocculant Storage Tank 124: Weighing means 125: Polymer flocculant 126: Supply port 128: Vibration damper 130: First solvent supply line 131a: First flow path switching valve 131b: second flow path switching valve 131c: Third flow path switching valve 131d: Fourth flow path switching valve 131e: Fifth flow path switching valve 132: Second solvent supply line 133: Washing line 134:Discharge port 140: Mixer 150: Densitometer 160: Perspective meter 181: Injection line 181-2: Branch line 182: Pump 185A: Injection point 185B: Injection point 186: Branch line 188: Return Line 189: Disposal line 190: Wastewater treatment facilities 191:Flocculation tank 191A: Slow mixing tank 191B: Rapid mixing tank 191C: Sedimentation tank 191-2: Another coagulation tank 192: Measuring equipment 192A: Measuring equipment 192B: Measuring device 192C: Measuring device 193: Mixing device 200: Control device 210: Arithmetic section 220: Control section 230: Storage section 240: Input section 250: Output section

Claims

1. A step A1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; Based on at least the measurement result in step A1, the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank is determined. 1 A step A2 of determining Dissolved concentration 1 A step A3 of supplying the aqueous solvent and the polymer flocculant to the dissolution storage tank in a ratio such that a polymer flocculant solution of A step A4 of dissolving the polymer flocculant in the dissolution storage tank in the aqueous solvent while stirring to prepare a polymer flocculant solution; A step A5 of supplying the polymer flocculant solution prepared in the step A4 to a flocculation tank; Including, A method for supplying a polymer flocculant solution.

2. Dissolved concentration 1 The method for supplying a polymer flocculant solution according to claim 1, further comprising carrying out step A4 under conditions of a stirrer rotation speed and a stirring time determined based on the above.

3. A step B1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; Based at least on the measurement results in step B1, the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank is 1 Step B2 of determining Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 and a step B3 of determining X 1 and X 2 and a step B4 of comparing X 1 >X 2 In the case of 1 , dissolved concentration X 2 Based on the amount of polymer flocculant solution already in the dissolution storage tank, the dissolution concentration X 1 A step B5 of determining the amount of polymer flocculant required to obtain a polymer flocculant solution; Step B6 of supplying the amount of polymer flocculant determined in step B5 to the dissolution storage tank; A process B7 of dissolving the polymer flocculant supplied to the dissolution storage tank in the existing polymer flocculant solution while stirring to prepare a polymer flocculant solution with a changed concentration; A step B8 of supplying the polymer flocculant solution having the changed concentration prepared in the step B7 to a flocculation tank; Including, A method for supplying a polymer flocculant solution.

4. a step C1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; Based at least on the measurement result in step C1, the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank is 1 and a step C2 of determining Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 and a step C3 of determining X 1 and X 2 and a step C4 of comparing X 1 <X 2 In the case of 1 , dissolved concentration X 2 Based on the amount of polymer flocculant solution already in the dissolution storage tank, the dissolution concentration X 1 A step C5 of determining the amount of aqueous solvent required to obtain a polymer flocculant solution; Step C6 of supplying the amount of aqueous solvent determined in step C5 to the dissolution reservoir; A process C7 of stirring the aqueous solvent supplied to the dissolution storage tank together with the existing polymer flocculant solution to prepare a polymer flocculant solution having a changed concentration; A step C8 of supplying the polymer flocculant solution having the changed concentration prepared in the step C7 to a flocculation tank; Including, A method for supplying a polymer flocculant solution.

5. A step D1 of measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of the coagulation flocs in the coagulation tank; Based at least on the measurement results in step D1, the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank is determined. 1 and a step D2 of determining Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 and a step D3 of determining X 1 and X 2 and a step D4 of comparing X 1 <X 2 In the case of 1 The aqueous solvent is supplied to the injection line at a flow rate ratio that results in a polymer flocculant solution of X. The existing polymer flocculant solution is simultaneously supplied from the dissolution storage tank to the injection line, and the two are mixed in the injection line by a mixer to obtain a dissolution concentration of X. 1 A step D5 of preparing a polymer flocculant solution changed to A step D6 of supplying the polymer flocculant solution having the changed concentration to a flocculation tank through an injection line; Including, A method for supplying a polymer flocculant solution.

6. a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; a dissolving and storing tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supplying device for supplying the polymer flocculant to the dissolution storage tank; a solvent supply line for supplying the aqueous solvent to the dissolution reservoir; A stirrer installed in the dissolution storage tank; an injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; A control device having a calculation unit and a control unit; Equipped with The calculation unit calculates the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measurement device. 1 can be determined, The control unit is a dissolution concentration X 1 The amount of the aqueous solvent supplied from the solvent supply line to the dissolution storage tank and the amount of the polymer flocculant supplied from the polymer flocculant supply device to the dissolution storage tank can be controlled so as to obtain a polymer flocculant solution of Polymer flocculant solution supply system.

7. The calculation unit of the control device calculates the dissolved concentration X 1 The polymer flocculant solution supply system according to claim 6, wherein the rotation speed and mixing time conditions of the agitator can be determined based on the above, and the control unit of the control device can operate the agitator under those conditions.

8. a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; a dissolving and storing tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supplying device for supplying the polymer flocculant to the dissolution storage tank; a solvent supply line for supplying the aqueous solvent to the dissolution reservoir; A stirrer installed in the dissolution storage tank; an injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 A concentration meter capable of measuring A control device having a calculation unit and a control unit; Equipped with However, the control device has a memory unit capable of storing information on the target dissolved concentration of the polymer flocculant when preparing the existing polymer flocculant solution in the dissolution storage tank, and the dissolved concentration is set to the dissolved concentration X 2 If it is possible to consider that the concentration is equal to or greater than the concentration of the liquid, the concentration meter may not be necessary. The calculation unit calculates the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measurement device. 1 Determining the dissolved concentration X 1 and solubility concentration X 2 and comparing X 1 >X 2 In the case of 1 , dissolved concentration X 2 Based on the amount of polymer flocculant solution already in the dissolution storage tank, the dissolution concentration X 1 The amount of polymer flocculant required to obtain a polymer flocculant solution of The control unit can control the amount of polymer flocculant supplied from the polymer flocculant supply device to the dissolution storage tank according to the determination of the calculation unit. Polymer flocculant solution supply system.

9. a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; a dissolving and storing tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supplying device for supplying the polymer flocculant to the dissolution storage tank; a solvent supply line for supplying the aqueous solvent to the dissolution reservoir; A stirrer installed in the dissolution storage tank; an injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 A concentration meter capable of measuring A control device having a calculation unit and a control unit; Equipped with However, the control device has a memory unit capable of storing information on the target dissolved concentration of the polymer flocculant when preparing the existing polymer flocculant solution in the dissolution storage tank, and the dissolved concentration is set to the dissolved concentration X 2 If it is possible to consider that the concentration is equal to or greater than the concentration of the liquid, the concentration meter may not be necessary. The calculation unit calculates the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measurement device. 1 Determining the dissolved concentration X 1 and solubility concentration X 2 and comparing X 1 <X 2 In the case of 1 , dissolved concentration X 2 Based on the amount of polymer flocculant solution already in the dissolution storage tank, the dissolution concentration X 1 The amount of aqueous solvent required to obtain a polymer flocculant solution of The control unit can control the amount of the aqueous solvent supplied from the solvent supply line to the dissolution reservoir tank according to the determination of the calculation unit. Polymer flocculant solution supply system.

10. a measuring device for measuring one or more conditions selected from the flow rate of the water to be treated flowing into the coagulation tank, the properties of the water to be treated flowing into the coagulation tank, and the coagulation state of coagulated flocs in the coagulation tank; a dissolving and storing tank capable of dissolving a polymer flocculant in an aqueous solvent and storing a polymer flocculant solution; A polymer flocculant supplying device for supplying the polymer flocculant to the dissolution storage tank; a first solvent supply line for supplying an aqueous solvent to the dissolution reservoir; A stirrer installed in the dissolution storage tank; an injection line for injecting the polymer flocculant solution discharged from the outlet of the dissolution storage tank into the flocculation tank; a second solvent supply line for supplying an aqueous solvent to the injection line; A mixing device for mixing the polymer flocculant solution flowing through the injection line and the aqueous solvent flowing through the second solvent supply line; Dissolution concentration X of polymer flocculant in the existing polymer flocculant solution in the dissolution storage tank 2 A concentration meter capable of measuring A control device having a calculation unit and a control unit; Equipped with However, the control device has a memory unit capable of storing information on the target dissolved concentration of the polymer flocculant when preparing the existing polymer flocculant solution in the dissolution storage tank, and the dissolved concentration is set to the dissolved concentration X 2 If it is possible to consider that the concentration is equal to or greater than the concentration of the liquid, the concentration meter may not be necessary. The calculation unit calculates the dissolved concentration X of the polymer flocculant in the polymer flocculant solution to be supplied to the flocculation tank based on the measurement result by the measurement device. 1 Determining the dissolved concentration X 1 and solubility concentration X 2 and comparing X 1 <X 2 In the case of 1 The ratio of the existing polymer flocculant solution to the aqueous solvent can be determined so that a polymer flocculant solution of The control unit can control the flow rate of the aqueous solvent supplied to the injection line via the second solvent supply line and the flow rate of the existing polymer flocculant solution supplied to the injection line from the dissolution reservoir tank so as to have a ratio according to the determination of the calculation unit. Polymer flocculant solution supply system.

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